This invention relates to a local conditioning induction-type apparatus employing primary inlet air as a power means for controlling temperature. In particular the present invention relates to a local conditioning induction-type apparatus for conditioning systems with four pipes of the secondary water and wherein the temperature is controlled by varying the secondary air flow passing through the heat-exchangers and a by-pass section, having valve assemblies for varying said air flow which are actuated by the same primary inlet air, at the usual feeding pressure of such air.
It is known that the induction-type conditioning apparatus for systems with four pipes of the secondary water essentially comprise a plenum chamber (possibly provided with a silencer) where primary air is fed at a pressure usually in a range of values from 15 to 100 Kg/m.sup.2 ; a row of nozzles wherein this pressure is converted into kinetic energy and then velocity; two water/air heat-exchangers, one fed by cooled water and the other by hot water; a by-pass section; valve assemblies for guiding the secondary air sucked from the room into a chamber which is placed downstream of the nozzles exclusively through either of the heat-exchangers, or the by-pass section only, the whole being constructed and connected so as to form a single unit.
It is also known that such conditioning apparatus use, for controlling the valve assemblies guiding the secondary air flow, actuators which may be pneumatic, electro-magnetic or electronic. When pneumatic actuators are used, one or more compressors compress air at a pressure of 70,000-80,000 Kg/m.sup.2 within suitable reservoirs from which compressed air, upon filtering, drying and pressure releasing to about 11,000 Kg/m.sup.2 is fed to all the control devices, in this specific case thermostats, by means of copper, steel or plastic material tubes. Air outflows from each thermostat at a pressure variable in a range from 0 to 1,100 Kg/m.sup.2 and the value of the varying pressure is a function of the temperature sensed by the thermostat, which in turn is connected with one or more actuators through other tubes, usually of copper or plastics. A compression station is therefore necessary and also a distribution system for the compressed air, with rather high costs of installation and operation.
Electric or electronic actuators are seldom used, due to their high prime cost and delicacy: on the other hand also in this case an electric feed line and connections between thermostats and actuators are required.